1. Technical Field
The present invention relates to an optical filter, an optical filter module, an analytical instrument, and an optical apparatus.
2. Related Art
An interference filter has been proposed that has a variable transmission wavelength (See JP-A-11-142752). As shown in FIG. 3 of JP-A-11-142752, there are a pair of substrates held in parallel to each other, a pair of multilayer films (reflecting films) formed on the pair of substrates so as to be opposed to each other and have a gap with a constant distance, and a pair of electrostatic drive electrodes for controlling the gap. Such a variable wavelength interference filter generates electrostatic attractive force in accordance with a voltage applied to the electrostatic drive electrodes to control the gap, thereby making it possible to vary the center wavelength of the transmission light beam.
However, it is difficult for such a variable wavelength interference filter to obtain a gap amount with accuracy due to a variation in the drive voltage caused by noise or the like.